Automatic transmission fluid level indicator

ABSTRACT

An automatic transmission fluid level indicator having a removable rod with an area of reduced diameter at and extending below the desired fluid level, a float including a conductive ring surrounding the reduced area, a circuit received in the rod connects a battery with a lamp or other indicator through the conductive ring upon sufficient descent of the float to indicate a significant decline in the fluid level. The float with the conductive ring is urged downwardly by a compression spring which, however, is insufficient in force to overcome the buoyance effect of the fluid upon the float, but when the rod is drawn out of the fluid, the circuit is automatically closed. A plug on top of the shaft provides for removal of the rod from the circuit. The amount of extension of the rod into the automatic transmission casing is adjustable whereby the amount of fluid loss to energize the indicator is also adjustable.

United States Patent 1191 Moore 154] AUTOMATIC TRANSMISSION FLUID LEVELINDICATOR [76] Inventor: Thomas Moore, 3440 Kansans nue, Baltimore, Md.21213 [22] Filed: Apr. 19, 1971 211 Appl. No.: 134,981

. [52] US. Cl, ..340/244 A, 200/84 R [51] Int. Cl.' ..G08b 23/00 [58]Field of Search ..340/244 A, 244 R [56] References Cited UNITED STATESPATENTS 1,244,962 10/1917 Derby ..340/244 A 2,804,517 8/1957 Ferry..340/244 A 2,915,605 12/1959 Freidell ..340/244 A 3,098,914 7/1963Giannino ....340/244 R 3,633,193 1/1972 Milo ..340/244 A PrimaryExaminer-Thomas B. Habeclter Attorney--Mason, Mason & Albright 1451 Apr.17, 1973 l 5 7 ABSTRACT 7 An automatic transmission fluid levelindicator having a removable rod with an area of reduced diameter at andextending below the desired fluid level, a float including a conductivering surrounding the reduced area, a circuit received in the rodconnects a battery with a lamp or other indicator through the conductivering upon suflicient descent of the float to indicate a significantdecline in the fluid level. The float with the conductive ring is urgeddownwardly by a compression spring which, however, is insuflicient inforce to overcome the buoyance effect of the fluid upon the float, butwhen the rod is drawn out of the fluid, the circuit is automaticallyclosed. A plug on top of the shaft provides for removal of the rod fromthe circuit. The amount of extension of the rod into the automatictransmission casing is adjustable whereby the amount of fluid loss toenergize the indicator is also adjustable.

9 Claims, 2 Drawing Figures AUTOMATIC TRANSMISSION FLUID LEVEL INDICATORBACKGROUND OF THE INVENTION A substantial source of difficulty withautomatic transmissions as are used in automobiles stems from leakage ofthe automatic transmission fluid. Unfortunately, the level of theautomatic transmission fluid is generally not checked with the samefrequency as the oil level in internal combustion engines because it isusually in a less accessible place and, more importantly, because themotor must be running when the test is conducted. A need exists, and hasexisted for some time, for a reliable fluid level indicator forautomatic transmissions.

SUMMARY OF THE INVENTION The invention relates to a fluid levelindicator for antomatic transmissions and, more particularly, to such anindicator which can be utilized to replace the dip stick presentlyutilized as an indicator in existing conventional automatictransmissions.

It has occurred to the inventor, that the tube presently utilized toreceive the dip stick in automatic transmissions of the type found inmost automobiles today, can also be employed for an automatic liquidlevel indicator which will signal the driver of the vehi-.

cle in the event that the automatic transmission fluid is dangerouslylow or has declined an amount which the operator of the vehicle desiresto be aware of; The liquid level indicator in accordance with myinvention has the advantage that it can also be utilized in the samemanner as the conventional dip stick to indicate directly the level ofthe automatic transmission fluid and at the same time provide a test forthe indicia means when the invention is so used. Further, the structureof the device is such that it may be adjusted so that it is energizedupon selected different reductions in the level of the transmissionfluid.

A fluid level indicator in accordance with my invention is relativelyeasy and inexpensive to manufacture, can be adapted to many types ofautomatic transmissions, is easily installed on existing automobiles,and is reliable in operation.

Other objects, adaptabilities and capabilities will be appreciated bythose skilled in the art as the description progresses, reference beinghad to the accompanying drawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS 1 FIG. 1 shows the invention inpartial cross section with the electrical circuit being shown, in part,schematically; and

FIG. 2 illustrates the closing of the indicator circuit when the amountof fluid in the automatic transmission is reduced by a predeterminedamount.

DESCRIPTION OF THE PREFERRE EMBODIMENT Referring to the Figures, thelevel indicator is designated generally by reference numeral 10. It isreceived in a tube 11 which extends generally upwardly from the casing12 which contains the automatic transmission and automatic transmissionfluid 14. It will be appreciated that the automatic transmission ofalmost all automobiles conventionally includes a tube 11, casing 12 aswell as, 'of course, fluid 14. However, in place of the dip stick whichis generally received within tube 11, level indicator is provided whichcomprises a shaft 15 which is threadably connected in its upper aspectto a tube cover 16 and is secured in a desired position relative to tubecover 16 by a lock nut 17. A handle 20 is connected to and extendsupwardly from the tube cover 16. In its lower aspect, the shaft 15contains a narrowed portion 21 under shoulder 22 and extending above acontact part 24 which is secured to portion 21 abutting shoulder 23 ofshaft 15. A ring float 25 which can be cork or any appropriate buoyantmaterial, but is preferably a hollow copper washer, surrounds portion 21so as to be movable therealong. Between shoulder'22 and ring float 25, acompression spring 26 is provided which urges ring float 25 downwardlytowards contact part 24, as shown in FIG. 1, but is insufficient instrength to overcome the buoyancy of ring float 25 in fluid 14. However,when fluid 14 is sufficiently low in casing 12 as shown in FIG. 2,compression spring 26 urges ring float 25 against part 24. In its lowestaspect, portion 30 of shaft 15, a pair of spring protectors 31 areconnected thereto which serve to center shaft 15 within tube 11 and andprevent ring float 25 from touching the sides of tube 11. Shaft 15 ispreferably composed of a non-conductive plastic, such as the plasticmaterial known as has a bayonet-type base and is normally mounted on agrounded dashboard 41 or other grounded portions of an automobile insuch a way that if electrical energy is provided via line 37, light bulbis energized. There are many arrangements whereby the bulb 40 can beattached to an automobile dashboard or otherwise so as to be visible tothe operator of the automobiles which are conventional and generallywidely known in the field to which the invention pertains. Accordingly,this is not described in detail inasmuch as it is not necessary for anunderstanding and use of the invention by a person skilled in the art.Also, it will be understood that a buzzer or hell can be'used insteadof, or in conjunction with bulb 40. I

Receptacle 36 has two sockets which are adapted to receive prongs from aplug 42 which is secured on the upper aspect of shaft 15. Preferably,plug 42 comprises simply two prongs extending from shaft 15 which areadapted to be received by receptacle so that each prong is electricallyconnected either to line 35 or line 37. Shaft 15 has a pair of wires 44and 45 extending through channels through its center to part 24. In part24, wire 44 electrically connects to a contact member 46 and wire 45electrically connects to a further contact member 47, which are includedin part 24.

In operation, with the fluid 14 at the level shown in FIG. 1, it is tobe understood that circuit 32 is opened between contact members 46 and47. However, if fluid 14 is lowered to the position shown in FIG. 2wherein there is, say, a 1 quart reduction in the volume of fluid,

float ring 25 provides a conductive bridge between the members 46 and47, thus closing the circuit and caus ing bulb 40 tobe energized. Inthis connection, it will be appreciated that if ring float 25 iscomposed of a conductive material, the float itself provides theconductive bridge. However, if this is not the case, then a conductivebridge must be provided on the float which can be, if the float shouldhappen to be cork, a thin gauge washer of copper or aluminum or thelike, connected to the lower surface of ring float 25.

If desired, the level indicator can be withdrawn by means of handle 20.When this occurs, the ring float 25, upon being drawn away from fluid14, is urged by compression spring 26 against the contact part 24 thusclosing circuit 32 and this provides a test bulb 40 to show whether itis operable. Without such means for periodic testing, the indicatormight provide false information for an extended period of time. In theevent that it is desired to remove indicator 10 some distance from thetube 11, receptacle 36 may be easily detached from plug 42 and thecircuit is such that the system is operable irrespective of whether plug42 and receptacle 36 are again joined as before or with the prongs ofplug 42 being received in opposite sockets of receptacle 36 Although Ihave described the preferred embodiment of my invention, it is to beunderstood that it is capable of other adaptations and modifications.For example, the same basic arrangement may be utilized as a lubricatingoil indicator.

Having thus described my invention, what I claim as new and desire tosecure by Letters Patent of the United States is:

1. In combination with a casing which contains a non-conductive fluid, afluid level indicator which comprises a shaft removably extending fromoutside of the casing into said fluid, a tube extending upwardly fromsaid casing receiving said shaft, a tube cover connected to said shaftcooperating with the top of said tube to retain said shaft in apredetermined position relative to said casing, float means carried bysaid shaft, said float means including conductive bridge means, saidfloat means being buoyant relative to said fluid and movable withinlimits relative to said shaft, electrically operated indicia means,resilient means mounted on said shaft relative to said float means,electrical energy producing means, and a circuit for connecting saidindicia means to said energy producing means, said circuit means beingreceived in said shaft and including a pair of contacts, said resilientmeans resiliently urging said float means toward said contacts with adownwardly directed force which is insuflicient to overcome the buoyancyof said float means in said fluid, said circuit means being in an openedcondition across said contacts, said contacts being aflixed to saidshaft relative to said float means whereby when said float means lowersa predetermined amount relative to said shaft due to a lowering of saidfluid in said casing or withdrawal of said shaft above said fluid, saidconductive bridge means conductively connects said contacts to closesaid circuit to energize said indicia means.

2. The apparatus of claim 1 wherein said float means comprises a ringwhich surrounds said shaft.

3. The apparatus of claim 2 wherein said ring is hollow and is composedof a conductive material.

4. The apparatus of claim 3 wherein said shaft incl desanarrowed rtionwhich receives saidrin 5. The apparatu of claim 4 wherein said re ilientmeans is mounted relative to said narrow portion and said ring whichurges said ring.

6. The apparatus of claim 5 wherein said resilient means comprises acompression spring which surrounds said narrowed portion.

7. The apparatus of claim 1 wherein adjustment means is included in theconnection of said shaft to said tube cover whereby the amount ofextension of said shaft into said casing is adjustable.

8. The apparatus of claim 1 wherein said casing contains an automatictransmission for a prime mover and said fluid is automatic transmissionfluid.

9. The apparatus of claim 1 wherein said circuit includes plug means andreceptacle in the upper aspect of said shaft.

1. In combination with a casing which contains a non-conductive fluid, afluid level indicator which comprises a shaft removably extending fromoutside of the casing into said fluid, a tube extending upwardly fromsaid casing receiving said shaft, a tube cover connected to said shaftcooperating with the top of said tube to retain said shaft in apredetermined position relative to said casing, float means carried bysaid shaft, said float means including conductive bridge means, saidfloat means being buoyant relative to said fluid and movable withinlimits relative to said shaft, electrically operated indicia means,resilient means mounted on said shaft relative to said float means,electrical energy producing means, and a circuit for connecting saidindicia means to said energy producing means, said circuit means beingreceived in said shaft and including a pair of contacts, said resilientmeans resiliently urging said float means toward said contacts with adownwardly directed force which is insufficient to overcome the buoyancyof said float means in said fluid, said circuit means being in an openedcondition across said contacts, said contacts being affixed to saidshaft relative to said float means whereby when said float means lowersa predetermined amount relative to said shaft due to a lowering of saidfluid in said casing or withdrawal of said shaft above said fluid, saidconductive bridge means conductively connects said contacts to closesaid circuit to energize said indicia means.
 2. The apparatus of claim 1wherein said float means comprises a ring which surrounds said shaft. 3.The apparatus of claim 2 wherein said ring is hollow and is composed ofa conductive material.
 4. The apparatus of claim 3 wherein said shaftincludes a narrowed portion which receives said ring.
 5. The apparatusof claim 4 wherein said resilient means is mounted relative to saidnarrow portion and said ring which urges said ring.
 6. The apparatus ofclaim 5 wherein said resilient means comprises a compression springwhich surrounds said narrowed portion.
 7. The apparatus of claim 1wherein adjustment means is included in the connection of said shaft tosaid tube cover whereby the amount of extension of said shaft into saidcasing is adjustable.
 8. The apparatus of claim 1 wherein said casingcontains an automatic transmission for a prime mover and said fluid isautomatic transmission fluid.
 9. The apparatus of claim 1 wherein saidcircuit includes plug means and receptacle in the upper aspect of saidshaft.